1. Field of the Invention
The present disclosure relates to a photoelectric conversion apparatus used for a scanner, a video camera, or a digital still camera.
2. Description of the Related Art
There has been offered an imaging apparatus that includes an analog/digital (A/D) conversion circuit and outputs a photoelectrically converted analog signal as a digital signal. Japanese Patent Application Laid-Open No. 05-095099 discusses an example photoelectric conversion apparatus. The photoelectric conversion apparatus prevents incursion of noise generated at a digital circuit unit into an analog circuit unit by separating a power source for the analog circuit unit from that for the digital circuit unit.
However, the conventional photoelectric conversion apparatus discussed in Japanese Patent Application Laid-Open No. 05-095099 has the following problems. Digital circuits used for the photoelectric conversion apparatus discussed in Japanese Patent Application Laid-Open No. 05-095099 include at least a digital circuit included in the A/D conversion circuit, a digital circuit for signal processing, and a digital circuit for pixel driving.
However, in the photoelectric conversion apparatus discussed in Japanese Patent Application Laid-Open No. 05-095099, a new problem such as the incursion of noise via the power or the ground among these different digital circuits, has not been found.
For example, in a pixel driving unit or the digital circuit included in the A/D conversion circuit, there is a period where many switches are simultaneously turned ON or OFF. In this case, large noise may enter the power source for the digital circuit or the ground, causing an erroneous operation of a signal processing unit operated at a relatively high speed corresponding to a signal output rate. This noise may be observed as random noise generated at a specific position in an image.